Is an IM Analyzer & Intermodulation Distortion Simulator the SAME THING?

[juniorexploder]

Hi,

This is my first post here so please be gentle!

I'm looking for an IM Analyzer to calibrate an old 24 track reel to reel deck. (according to their manual)....

I keep seeing LOTS of these RDL Intermodulation Distortion Simulators online...

**broken link removed**

Pardon my tech-less-ness but is anyone familiar with these units?

Basically, I need to connect the IM Analyzer to the input and output of the track I'm testing and adjust a trimpot on the tape deck until a minimum distortion reading is obtained....

(I couldn't use a Harmonic Distortion Analyzer , could I?)

AGain, Pardon my ignorance!...Just trying learn!

Thanks!

 

[JimB]

If you read the information about the analyser in your link, you will see that it is a piece of RF test equipment intended for use at 800-900Mhz.
It is used for testing cellphone systems and basically useless for testing an audio tape recorder.

JimB

 

[juniorexploder]

If you read the information about the analyser in your link, you will see that it is a piece of RF test equipment intended for use at 800-900Mhz.
It is used for testing cellphone systems and basically useless for testing an audio tape recorder.

Thanks Jim, I didn't see an explanation in the link that mentioned cell phone application... nor did the test instructions in the tape deck manual specify the frequency of a test signal...so....

And not REALLY knowing what an IM analyz(S)er does in the first place...I plead temporary ignorance!

Just learning here! Cheers!

 

[JimB]

Intermodulation is a form of distortion caused by non-linearity in a circuit.
(But then all distortion is caused by non-linearity).

Intermodulation
If you put two signals in to a "system", you hope to get only two signals out.
With Intermodulation distortion if you put in two signals of frequency f1 and f2, you will get out of the system not just f1 and f2 but also (2xf1 - f2), (2xf2 - f1), (3xf2 - 2xf1), (3xf1 - 2xf2), etc etc.

In a non-linear system you will also get harmonic distortion, where if you put in a signal of frequency f, you will get out signals at f, 2f 3f, 4f etc.

So having gone all around the houses with this, unless you are looking for perfection, don't worry too much about the intermodulation.
If you have a means of measuring harmonic distortion, I suggest that you use that I am sure that it will be good enough for most purposes.

At this point I must confess that I have no experience of 24 track tape systems, I am sure that someone here on ETO does have experience and will correct me if I am wrong in my assumptions.

(Afterthought, does a 24 track tape do some tricky multiplexing of audio signals on to multiple carriers?
If so the the intermod measurements may well be necessary.)

JimB

 

[audioguru]

(Afterthought, does a 24 track tape do some tricky multiplexing of audio signals on to multiple carriers?

TAPE?? Does anybody use tape anymore?? I haven't used tape for about 20 years or more. Everything became digital then I recorded and played back from the hard drive on my huge and heavy MP3 player (that I got for free and I fixed).

 

[juniorexploder]

TAPE?? Does anybody use tape anymore?? I haven't used tape for about 20 years or more. Everything became digital then I recorded and played back from the hard drive on my huge and heavy MP3 player (that I got for free and I fixed).

Lots of folks still use tape! (even up there in the Great White North!)...I've got 10 open reel machines of different sizes ( a few that I got for free and I fixed!) What's fascinating to me is that (especially the ones made in the 80's and 90's) are the absolute zenith of electronic/mechanical/audio engineering....really spectacular pieces of kit! AND when they're properly calibrated they sound amazing (notice how I totally avoided any analog vs. digital comparisons?...not stepping in THAT snakepit!)...;-)

 

[ChrisP58]

Afterthought, does a 24 track tape do some tricky multiplexing of audio signals on to multiple carriers?

JimB

Nope. Two inch wide tape with a tall, 24 channel head. And you could record on some tracks while playing back from others.

 

[audioguru]

My first job was with Philips on their car radio production line. The radios used 8-track tape players then Philips invented the Compact Cassette.
It played voices pretty well but I souped up the cassette recorder/player in my car so it was truly hi-fi for playing music. My ideas helped the Compact Cassette become hi-fi.

 

[JimB]

ChrisP58
That is some machine, it must have cost a fortune in moving coil meters to build that thing!
JimB

PS What is a "metal whore" ?